diff options
Diffstat (limited to 'drivers/infiniband/hw/hfi1/efivar.c')
| -rw-r--r-- | drivers/infiniband/hw/hfi1/efivar.c | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/drivers/infiniband/hw/hfi1/efivar.c b/drivers/infiniband/hw/hfi1/efivar.c new file mode 100644 index 0000000000..2b5d264f41 --- /dev/null +++ b/drivers/infiniband/hw/hfi1/efivar.c @@ -0,0 +1,138 @@ +// SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause +/* + * Copyright(c) 2015, 2016 Intel Corporation. + */ + +#include <linux/string.h> +#include <linux/string_helpers.h> + +#include "efivar.h" + +/* GUID for HFI1 variables in EFI */ +#define HFI1_EFIVAR_GUID EFI_GUID(0xc50a953e, 0xa8b2, 0x42a6, \ + 0xbf, 0x89, 0xd3, 0x33, 0xa6, 0xe9, 0xe6, 0xd4) +/* largest EFI data size we expect */ +#define EFI_DATA_SIZE 4096 + +/* + * Read the named EFI variable. Return the size of the actual data in *size + * and a kmalloc'ed buffer in *return_data. The caller must free the + * data. It is guaranteed that *return_data will be NULL and *size = 0 + * if this routine fails. + * + * Return 0 on success, -errno on failure. + */ +static int read_efi_var(const char *name, unsigned long *size, + void **return_data) +{ + efi_status_t status; + efi_char16_t *uni_name; + efi_guid_t guid; + unsigned long temp_size; + void *temp_buffer; + void *data; + int i; + int ret; + + /* set failure return values */ + *size = 0; + *return_data = NULL; + + if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) + return -EOPNOTSUPP; + + uni_name = kcalloc(strlen(name) + 1, sizeof(efi_char16_t), GFP_KERNEL); + temp_buffer = kzalloc(EFI_DATA_SIZE, GFP_KERNEL); + + if (!uni_name || !temp_buffer) { + ret = -ENOMEM; + goto fail; + } + + /* input: the size of the buffer */ + temp_size = EFI_DATA_SIZE; + + /* convert ASCII to unicode - it is a 1:1 mapping */ + for (i = 0; name[i]; i++) + uni_name[i] = name[i]; + + /* need a variable for our GUID */ + guid = HFI1_EFIVAR_GUID; + + /* call into EFI runtime services */ + status = efi.get_variable( + uni_name, + &guid, + NULL, + &temp_size, + temp_buffer); + + /* + * It would be nice to call efi_status_to_err() here, but that + * is in the EFIVAR_FS code and may not be compiled in. + * However, even that is insufficient since it does not cover + * EFI_BUFFER_TOO_SMALL which could be an important return. + * For now, just split out success or not found. + */ + ret = status == EFI_SUCCESS ? 0 : + status == EFI_NOT_FOUND ? -ENOENT : + -EINVAL; + if (ret) + goto fail; + + /* + * We have successfully read the EFI variable into our + * temporary buffer. Now allocate a correctly sized + * buffer. + */ + data = kmemdup(temp_buffer, temp_size, GFP_KERNEL); + if (!data) { + ret = -ENOMEM; + goto fail; + } + + *size = temp_size; + *return_data = data; + +fail: + kfree(uni_name); + kfree(temp_buffer); + + return ret; +} + +/* + * Read an HFI1 EFI variable of the form: + * <PCIe address>-<kind> + * Return an kalloc'ed array and size of the data. + * + * Returns 0 on success, -errno on failure. + */ +int read_hfi1_efi_var(struct hfi1_devdata *dd, const char *kind, + unsigned long *size, void **return_data) +{ + char prefix_name[64]; + char name[128]; + int result; + + /* create a common prefix */ + snprintf(prefix_name, sizeof(prefix_name), "%04x:%02x:%02x.%x", + pci_domain_nr(dd->pcidev->bus), + dd->pcidev->bus->number, + PCI_SLOT(dd->pcidev->devfn), + PCI_FUNC(dd->pcidev->devfn)); + snprintf(name, sizeof(name), "%s-%s", prefix_name, kind); + result = read_efi_var(name, size, return_data); + + /* + * If reading the lowercase EFI variable fail, read the uppercase + * variable. + */ + if (result) { + string_upper(prefix_name, prefix_name); + snprintf(name, sizeof(name), "%s-%s", prefix_name, kind); + result = read_efi_var(name, size, return_data); + } + + return result; +} |